feat: v0.5.0 release (Theming, Refactoring, CI Updates)

[ahnafnafee]

Summary

Major update (v0.5.0) focusing on codebase modularity, UI modernization, and CI/CD improvements.

Key Changes

• Refactoring: Split extension.ts into modular components (config, preview, webview).
• UI/UX: Added native VS Code theme support (auto light/dark mode) and improved navigation UI. Removed Bootstrap.
• CI/CD: Upgraded workflows to Node.js 22 LTS, switched to Yarn, and updated GitHub Actions.
• Documentation: Updated README.md, added TESTING.md guide.
• Cleanup: Renamed test_eps -> examples and removed unused files.

Testing

• Verified manual preview execution with various .ps files.
• Confirmed theme switching updates the webview immediately.
• Validated CI builds pass with the new Node 22 environment.